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be said to be ferns, some firs, a few palms, a few species un- 
known, and no exogens. One never differs in opinion, but 
with regret, from the ever-honoured name of Humboldt, but 
I do think a century is too long for the deposition of eight 
French lines ; and, on the other hand, a century is too short 
for the nine-inch bed of coal at Bolton, with the large trees 
grown upon it. 
Mr. R. Hunt says, " Without the light of the sun, no 
" tropical plant can be produced." But perhaps there may 
be some little error in requiring one great phenomenon to do 
what a great number of little disturbing causes may have 
effected. We know that the sun's rays are not required to 
produce that luxuriant, though it may be pale and almost 
flowerless, flora of our present woods, beneath the rich 
spreading oaks, elms, and ashes, on the steep slopes of our 
shaded glens, in the shadow of our dark pointed rocks, where 
the rays of the sun never shone, where annually rises the 
brake or common fern, with a variety of other annuals to the 
height of a man, and with a luxuriant compactness that 
makes it difficult to wade through them in the beginning of 
autumn. And if you work down to the roots of the present 
growing ferns, it will be found that many years are required 
to produce their partial decomposition. Perhaps rivers from 
the tropics, having connection with a similar stream to the 
gulf stream, hot springs, and certainly a more moist and 
extra quantity of carbon in the highly charged atmosphere, 
may probably produce these so-called tropical plants. But 
from whatever phenomena, causes, or length of time coal is 
in forming, I think the variety of minor disturbing causes is 
more consistent than calling to our aid the axial changes of 
our planet ; for however slow we consider the formation of 
coal to have been, we must allow a very rapid deposition in 
some cases of the intermediate strata of shale and sandstone, 
as also bands of coal. For instance, the large fossil tree at 
f2 
